Boat propulsion device



Feb. 5, 1952 D, K, WARNER 2,584,766

BOAT PROPULSION DEVICE Filed Dec. 22, 1945 Patented Feb. 5, 1952 UNTED STATES PATENT @.F'FECE 1 Claim.

The object of this invention is to furnish a lower unit for a boats outboard motor which will permit operation of the boat in shallow water, eliminate the possibility of striking the propeller on bottom or on iloating objects, avoid cutting sh lines with the propeller, eliminate underwater gears and other items at present subject to rapid wear; and avoid the propeller tip losses, which are apt to be excessive on the very small propellers used with high speed outboard motors due to the excessive twist given the propeller wake.

Secondary objects are: to provide an air lm between the water discharged bythe propulsion unit and the surface of the water over which it is discharged, in order that it may flow away from the boat with less resistance and less minglingr with the water which is at rest on the surface which would thereby tend to dam up the discharge jet; and to provide means for deflecting the jet for steering.

The device is intended primarily for use with an air cooled ve cylinder two cycle motor equipped with a transmission permitting direct drive; or drive through epicyclic planetary gears of ve and one half to one reduction, shown in application 337,683 now 2,410,471 dated Novem-i ber 5, 1946, and application 634,811, so that when trolling at four miles per hour the throttle may be wide open at low propeller speed on direct drive, and so that the engine may be speeded up one hundred times faster to give the power for faster return home, this being made possible by the gear reduction. If the device is to be used with conventional Outboards a water pump would, of course, be provided, but because the new motor uses neither pump nor fan neither are shown here.

Fig. 1 is a sectional View the outboard motor.

Fig. 2 is a front elevation of same. viewed from boat or the right side of Fig. 1.

Fig. 3 is a rear View; Fig. 4 a top View; and Fig. 5 a view of the device from beneath it.

The device is to be tted to a boat with a transom I which slopes upwardly rearwardly, or is vertical. By flange 3 the elbow 4 is bolted to the boats stern. Inside the elbow the propeller 5, is mounted on shaft 6, the latter being supported by bushing 'I and thrust rolling ball bearing 8 which, in turn, is held in place by torque tube 9. The bushing 'l is mounted at the bottom of tube I and rigidly fixed by a turbine bucket shaped arm having trailing edge I I and leading edge IIA, said arm II extended to the port so as to reverse the flow from the blade moving forwardly on the port side of the boat, as shown in section I 2A, past the rudder I3, which is turned by shaft i 4 so that the jet of water may be thrown to either side and thus steer the boat.

The inlet openings I5 are protected from driftwood by bars I6 and sides l'I. The boat is proof the lower unit of vided with two keels I8 each terminating just ahead of the stern in front of the sides Il. The screws, or pins, i9 fasten these sides of the inlet to the bottom of the boat, and the joint 26 between boat and upper part of opening is packed to prevent leakage of air into the water stream. The sides I'I are carried rearward at the height shown by dotted line 2! until they blend with the enlarging diameter of the elbow. Between the sides and the iront curved wall 36 of the elbow the space is left without a top so that air may pass down as shown by dotted. arrows under wall 22 of elbow in the passage 23 and thence out through opening 26 behind step 23. This air passes under rear step 26 to form an air nlm between the water discharged from opening at 2 and the surface of the water on which the boat is riding so that the discharge stream may quickly spread out without building a wave behind the boat.

The discharge opening 2l is of semicircular form, its top shown in dots 28 and the nat bottom at 29.

Having thus described my invention what I claim as new and wish to secure by Letters Patent is:

In a boat propulsion device including a housing and a screw propeller and a propeller shaft mounted therein wherein said housing is formed in the general configuration of an elbow in the saine vertical plane of said housing and having a face sloping forwardly and upwardly, said housing extending rearwardly therefrom and thence bending rearwardly downwardly, the downwardly bent portion formed to provide a lesser cross sectional area than said entrance and terminating in a discharge opening, that improvement which comprises locating said propeller generally in said entrance with said shaft coaxially therewith and upwardly extended, vwhereby the turning of said shaft accelerates water rearwardly.

DOUGLAS K. WARNER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 127,825 Babbitt June 11, 1872 1,007,583 Loetzer Oct. 31, 1911 1,110,522V Ackerman Sept. l5, 1914 1,262,942 Graumlich Apr. 16, 1918 1,806,651 Schmidt May 26, 1931 2,291,937 Young Aug. 4, 1942 FOREIGN PATENTS Number Country Date 22,222 Great Britain Oct. 9, 1911 210,930 Great Britain Feb. 14, 1924 606,019 Germany Nov. 26, 1934 

